1. Field of the Invention
The invention relates to a coil arrangement for an optical scanner, which arrangement has a supportlessly wound first coil, to the circumference of which there is attached at least one further coil, the axis of which thereby runs essentially perpendicular to the circumference of the first coil.
2. Description of Related Arts
Optical scanners are used for the scanning of an information track on an optical recording carrier, their lens system on the one hand being focused on an information track and on the other hand being set, in a direction transverse to the information track, to the track centre, for which purpose on the one hand a scanning setting of the lens system in relation to the optical recording carrier is necessary and on the other hand an adjusting movement of the lens system in a direction transverse to the information track is necessary. Accordingly, the lens system of such an optical scanner is arranged on an adjustable mount, which can perform the two abovementioned movements. A coil arrangement, which interacts with a magnet system, serves for the generation of such movements, the coil arrangement being fed electric control signals, as a result of which relative movements between the coil arrangement and the magnet system are effected and these are then transmitted to the mount of the lens system.
A coil arrangement of the generic type specified at the beginning, such as is known, for example, from an optical scanner described in German Offenlegungsschrift 3,831,425, has for this purpose a supportlessly wound first coil which is designed rectangularly in cross-section perpendicular to its coil axis and to which there are attached on one of its longer circumferential sides two flatly designed, likewise supportlessly wound further coils, which in practice is accomplished by an adhering operation. The production of such a coil arrangement is relatively complicated and very tricky, since the coils used are wound from a very thin wire and are relatively small, an adhering operation also being necessary in addition, which is well known often to entail difficulties, in particular in mass production. In addition, the stability of such a coil arrangement is relatively low, since the coils used are supportlessly wound, as a result of which difficulties may likewise arise during the course of production of an optical scanner, on which particular accuracy requirements are made.